Rapid progress in genomics, proteomics, and cell analysis has pushed the biotechnology sector to develop faster and more efficient devices for analyzing biological samples. Accordingly, the biotechnology sector has directed substantial effort toward developing miniaturized microfluidic devices, often termed labs-on-a-chip, for sample manipulation and analysis. Such devices may analyze samples in small volumes of liquid, providing more economical use of reagents and sample, and in some cases dramatically speeding up assays. These devices offer the future possibility of human health assessment, genetic screening, and pathogen detection as routine, relatively low-cost procedures carried out very rapidly in a clinical setting or in the field. In addition, these devices have many other applications for manipulation and/or analysis of nonbiological samples.
Despite the sophistication of the electronics industry, microfluidic devices have not sufficiently integrated electronic circuitry into the combined electrical and fluidic manipulation of samples. For example, one class of microfluidic devices lacks the capability to electrically manipulate samples. This first class of devices may be inadequate for the control and monitoring of assay conditions in small volumes. Furthermore, devices of this first class may not be able to perform sample analyses of charged analytes, such as nucleic acids, on a time-scale afforded by electrical manipulation. A second class of microfluidic devices affords electrical, but not electronic, sample and fluid manipulation. This second class of devices may be capable of combined electrical and mechanical fluid/sample manipulation. However, without the capability of electronic switching, this second class cannot control a high density of electrical devices in the small area that is available proximate the fluid networks of such microfluidic devices. Accordingly, this second class also is limited in its ability to perform carefully regulated sample manipulations in small volumes. A third class of microfluidic devices includes integrated electronic circuitry to manipulate samples and fluids electronically. However, this third class of devices does not integrate the electronic circuitry effectively into the architecture of fluid flow paths within the devices.